The installation of electrical wires in homes and commercial buildings requires encasing the wire in conduit for safety, aesthetic and structural considerations. Conduit is sold commercially in straight pieces of varying length and material. In many applications, an installer must bend conduit to accommodate a physical structure in the routed path of the conduit. For instance, conduit is routinely bent to avoid a beam, pillar or other obstruction in a building.
In such a circumstance, the installer typically creates an offset in the conduit. That is, the installer bends the conduit in a first direction to go around the obstruction, and after extending a short distance, bends the conduit in a second, but opposite direction. In this way, the conduit continues in a direction substantially parallel to its original course, but offset in order to avoid the obstruction. After passing the obstruction, the craftsman installing the conduit may bend the conduit a third and fourth time in opposite directions so that the conduit resumes its initial path.
Bending an offset into conduit is a labor intensive job that conventionally requires a great deal of time, knowledge and experience. A single offset generally takes two installers the better part of a hour to create on conduit trade sizes over two inches. Even the most skilled installers will routinely misjudge where an offset bend should be placed, resulting in the bend being re-accomplished and/or the conduit being discarded. In fact, the industry generally budgets for and tolerates about ten percent wastage with regard to conduit. That is, one out of every ten feet of purchased conduit will typically be rendered unusable by the end of an installation job. Because of costs associated with these labor and material requirements, the installation of conduit accounts for a significant portion of a construction budget.
To mitigate these costs, manual, electric, hydraulic and other mechanical conduit benders have been developed to assist installers in making offsets. A typical hand bending machine may include a handle screwed into a body having an arcuate shoe at the bottom with a groove to accommodate the conduit. The body may also have a hook which hooks around the conduit in the groove. The installer may bend the conduit by exerting a force on the handle to roll the shoe along the conduit and achieve a bend. Machine benders generally rely on the same principles, however, include hydraulics or other sources to power a ram that exerts power on a shoe to bend the conduit.
These benders, however, do not meaningfully assist an installer in deciding where bends should be made in a conduit to create a desired offset. Despite the criticality of bend placement, an installer is relegated to estimating, or eyeballing, where such bends should be made along the length of the conduit. This industry practice of eyeballing often degenerates into unreliable trial and error even for the most skilled installers. Imperfect offsets translate into the installer having to scrap the conduit piece, or where possible, re-accomplish the bend. Either scenario translates into undesirable waste and expense.
Moreover, conventional practices require that the conduit be disengaged from the bending tool in order to determine the position of a subsequent bend. This is required, in part, because the installer must eyeball angles to determine the next bend point. Taking the conduit in and out of the bending machine requires at least two installers and represents a significant labor inefficiency.
Job manuals and training provide little practical remedy for inefficiencies associated with determining an offset bend. While some manuals provide estimated distance dimensions, the limited number of bend angles associated with these estimates limits their practical utility. For example, conventional bending manuals do not address, and thus, discourage the use of bend angles that deviate from standard 15°, 30° or 45° angle bends. As can be appreciated, bends of alternate and varying degrees are desirable given certain practical circumstances of a particular installation. Moreover, it is very difficult to accomplish one of the prescribed bend angles with enough precision to make the manual estimates worthwhile. In any case, most installers are reluctant to use such manuals and associated multipliers because of the time requirements and inherent complexities of such calculations.
Conventional methods also require the installer to take the diameter of the pipe into account when calculating bend centers needed to estimate bend distances. For instance, the conduit diameter may affect where the installer will interpolate the center of a first bend as being. An error in this estimate has a cascading affect on subsequent estimates. This diameter variable thus further complicates field calculations or eyeball estimates, contributing to incorrect offsets and other inefficiencies.
Errors stemming from imperfect bend distancing are compounded where angles of associated offset bends do not match. However, conventional benders generally rely on user judgment to indicate stop points to achieve a desired degree of bend. Some tools have visual markings along the anvil, or ram, side that generally indicate angles of a bend. As above, however, reliance on user judgment or on visual markings offers only a limited accuracy of bend.
For all of these reasons, what is needed is an improved manner for bending conduit.